Micromirror devices for use, for example, in optical communications techniques and for optical matrix switches are known in the art. For example, apparatus useful for such communications links is known from U.S. Pat. No. 6,295,154, entitled “Optical Switching Apparatus”, commonly assigned herewith and incorporated herein by reference. This patent discloses a micromirror assembly for directing a light beam in an optical switching apparatus. As disclosed in this patent, which reflects the light beam in a manner that may be precisely controlled by electrical signals, the micromirror assembly includes a silicon mirror capable of rotating in two axes. One or more small magnets are attached to the micromirror itself; a set of four coil drivers are arranged in quadrants, and are controlled to attract or repel the micromirror magnets as desired, to tilt the micromirror in the desired direction.
Micromachined mirrors for two-dimensional scanning at different rates suitable for television display are known, for example, in U.S. Pat. No. 5,629,790. The mirrors may be electrostatically or electromagnetically deflected and rely on the torsional forces in the flexible hinges to restore the mirror to its original position in a resonance scanning technique. The magnetic deflection technique uses a galvanometer type drive in which the coil is formed around the periphery of the mirror and a permanent magnet is provided external to the mirror. The mirrors operate at resonant frequency as shown in the Table 1 in the patent, and can be utilized along with modulated laser light to form television receiver images as a compact substitute for a cathode ray tube.
It is desirable to have a very small mirror, on the order of 1 mm2, which could be built into a compact package and used for scanning at a vertical scanning frequency of 50 or 60 Hz, for example. This mirror would not utilize a resonance scanning frequency. If a magnetic drive were utilized which requires the mounting of a permanent magnet on the mirror, the mass of the permanent magnet would be larger than the mass of the mirror, which would place undue stresses on the mirror and make for an inefficient operation. Thus, there is a need for a mirror which utilizes a different drive system.